The invention relates to a valve, in particular a process valve, comprising a valve housing through which a process medium can flow and in which a valve seat is located, which surrounds a through-flow opening and to which a valve member mounted on a spindle is assigned in such a way that the valve member can be moved by means of an actuating stroke of the spindle between a blocking position in which the valve member bears against the valve seat in a process medium-tight manner and an open position in which the valve member is raised off the valve seat, and wherein an interface for coupling a drive unit generating the actuating stroke of the spindle is provided on the valve housing, and wherein a sealing device through which the spindle passes and which comprises a seal assembly including sealing means bearing against the spindle while forming a seal is accommodated in the valve housing.
A valve of this type is, for example, known from EP 2 110 585 A1. The so-called angle seat valve disclosed in this publication comprises a valve housing through which a process medium can flow. A valve seat bounding a through-flow opening is formed in the valve housing. The valve seat is assigned a sealing element which is supported by a spindle driven to perform a linear movement via a pneumatic actuator, so that the through-flow opening can be optionally opened or closed by the sealing element. A typical feature of such angle seat valves is that the valve seat area spanned by the valve seat is oriented at an angle to the flow direction of the process medium. As a result, the spindle is likewise oriented at an angle to the flow direction of the process medium and the actuating stroke is inclined accordingly. In the prior art referred to above, an interface for coupling the pneumatic drive unit is formed on the valve housing. For this purpose, a pipe is screwed into a connector projecting at an angle from the rest of the valve housing. The pipe is a part of the pneumatic actuator, because the cylinder of the pneumatic actuator is secured to the pipe end opposite the pipe end which is screwed into the valve housing. For this purpose, the pipe has a mounting section which has a larger diameter than the rest of the pipe and which also forms the end cover section of the cylinder housing, in which a piston is movably guided by means of the application of compressed air, the piston dividing the interior of the cylinder into two chambers. In addition, the pipe has a further purpose, i.e. the accommodation of a sealing device with a seal assembly in the form of a V-sleeve packing preloaded by a spring likewise located in the pipe.
The stroking movement of the spindle results in the wear of the V-sleeves of the V-sleeve packing, forcing their replacement. To replace the seals, however, the entire pneumatic actuator has to be removed from the valve housing. Furthermore, the pipe has to be separated from the rest of the pneumatic actuator to make the sealing device accessible. This is a very complex and expensive operation.
Another angle seat valve is known from DE 22 52 532. The angle seat valve disclosed there comprises a valve housing with an interface for coupling a pneumatic actuator. In this case, a support bushing is provided through which the valve spindle passes and which accommodates a V-sleeve packing. The support bushing is inserted into a connection of the valve housing, an axial stop in the form of an annular shoulder on the connection being provided. The support bushing in turn has the interface for coupling the pneumatic actuator. This is assembled with the support bushing before the latter is inserted into the connection; in this process, a washer separate from the support bushing comes into contact with the top side of the support bushing. After the support bushing together with the pneumatic actuator has been inserted into the connection, it is secured against axial movement out of the connection by means of a sleeve nut tightened onto a male thread formed on the connection.
In order to replace the seals, the sleeve nut first has to be released, and the support bushing has to be removed from the valve housing together with the pneumatic actuator. This is followed by the complicated removal of the support bushing from the spindle.